Mechanism And Operating Characteristics Of Orbital Friction Vibration Actuator

Rotary friction welding and linear friction welding which have advantages of low energy consumption, no pollution and high production efficiency are solid state joining process technique, however, the drawback of the non-uniform heat generation limits their further applications. Orbital friction welding takes into consideration the advantages of the rotary friction welding and linear friction welding, and has the characteristic of uniform heat generation and develops rapidly in recent years. Orbital Friction Vibration Actuator(OFVA) has an important research value as a core component of orbital friction vibration machine. However, the magnetic circuit of OFVA is special and its calculation and analysis have specificities. At present, the research on OFVA is few. In this paper, Electromagnetic OFVA(EOFVA) and Permanent Magnet OFVA(PMOFVA) are put into focus, the problems of mechanism, vibration characteristic, characteristic of electromagnetic force and dynamic operating characteristics have been studied.The mechanism of OFVA is studied. The expressions of the electromagnetic forces which drive the moving component to produce elliptical and circular motion trajectories are derived. Based on the result, the expressions of amplification factor of systematic vibration amplitude of OFVA under no-load and on-load conditions are derived furtherly. Variation of amplification factor of systematic vibration amplitude with vibration frequency and the major factors which have impact on the systematic vibration amplitude are studied. The results show the expressions of amplification factor of systematic vibration amplitude are same under no-load condition and the expressions of amplification factor of systematic vibration amplitude under on-load condition have a certain relationship with those of factor under no-load condition.Operating characteristics of EOFVA are studied. Based on the results of three-dimensional finite element numerical calculation, the simulation models which are driven by three-phase balanced sinusoidal current and voltage source are established. The roundness errors of motion trajectories which the actuators driven by current and voltage source produce are analyzed. The results show the roundness error of motion trajectory with the voltage source is smaller than that with current source when the systematic vibration amplitudes remain the same. The operating characteristics of EOFVA are calculated and analyzed. The results show systematic vibration amplitude increases linearly as the current amplitude increases under the same vibration frequency. The experiments of static electromagnetic force-displacement characteristic and operating characteristic validate the accuracy of simulation results.A type of structure of PMOFVA which is used to weld metal parts is proposed. According to the structural feature of the actuator, its electromagnetic field model can be simplified into single-phase permanent magnet friction vibration actuator. Influence of pole arc coefficient on thrust produced by single-phase permanent magnet friction vibration actuator unit is analyzed comparatively as five types of magnet pole structure are employed. The results show the actuator can produce larger thrust and less stator coreloss as the quasi-Halbach array is employed. Influences of structural parameters of single-phase permanent magnet friction vibration actuator on thrust and its fluctuation are analyzed. Finally, three-dimensional finite element method is used to calculate static electromagnetic force-displacement characteristic of the actuator and experiment is carried out to validate.Operating characteristics of PMOFVA are studied. Based on the results of three-dimensional finite element numerical calculation, the simulation models which are driven by two-phase balanced sinusoidal current and voltage source are established. The roundness errors of motion trajectories which the actuators driven by current and voltage source produce are analyzed. The results show the roundness error of motion trajectory with the voltage source is smaller than that with current source when the systematic vibration amplitudes remain the same. The operating characteristics of PMOFVA are calculated and analyzed. The results show systematic vibration amplitude increases linearly as the current amplitude increases under the same vibration frequency.